OEM radios are switched off and on via a network signal
A third party radio will not just drop in and work
You either need a CANBUS converter box thingy or patch in an ignition controlled live wire
If you post in the I.C.E. Section you should get some help as people have gone down these route before you
You can also get a Bluetooth audio transmitter that plugs into the cigarette lighter socket and transmits from your phone to a spare radio channel on any radio